Catalysts of metallocene type are particularly of interest when it is proposed to prepare polymers or copolymers of reduced polydispersity, for example in the region of 2. However, these catalysts are generally suited to homogeneous polymerization processes and there exists no solid catalytic component of metallocene type suited to heterogeneous polymerization processes, that is to say to suspension or gas-phase processes, which exhibits high activity and which is easy to prepare. Furthermore, solid catalytic components of metallocene type are prepared so that the metallocene entity is in fact adsorbed at the surface of a solid without a strong bond with the latter. For this reason, a loss in activity is commonly observed over time, the metallocene entity having a tendency to be released from the surface of the solid. This problem is, for example, more particularly significant in the case of suspension polymerization or copolymerization processes.
The patent application published under No. J07316219 describes a catalytic component comprising a stage of reaction between a silica and SiCl.sub.4 and its use in the polymerization of propylene. Such a component exhibits a very low activity in the polymerization of an olefin such as propylene or ethylene.